1. Field of the Invention
The present invention relates to an optical head for optically recording and/or reproducing data.
2. Description of the Related Art
An optical head for recording and/or reproducing data is described in Jap. Pat. Appln. KOKAI Publication No. 4-206046. FIG. 16 shows the structure of such an optical head. As shown in this figure, a semiconductor laser 11 and a light receiving element 14 are provided in an enclosure case 16, and the light receiving element 14 is arranged such as to be tilted by 45 degrees with respect to the semiconductor laser 11. A window 17, through which a light beam reflected on the light receiving element 14 passes, is formed in the enclosure case 16, and an objective lens 13 for focussing the light beam on an optical disk (not shown) is mounted on the window 17.
Light emitted from the semiconductor laser 11 is reflected by the light receiving element 14, and irradiated on the recording surface (not shown) of the optical disk by the objective lens 13. The reflection light modulated by the recording surface of the optical disk is collected by the objective lens 13 and made incident on the light receiving element 14.
As shown in FIG. 17, the light receiving element 14 has two detectors A and B. The detector A receives the reflection light beam from the optical disk, and a reproduced signal, a focussing error signal and a tracking error signal are obtained based on this reflection light beam. The detector B receives the light beam output from the semiconductor laser 11, and the output is used to control the light emission amount of the semiconductor laser 11.
With this optical head, one semiconductor substrate, on which the light receiving element is formed, functions as both a mirror for reflecting the light beam from the semiconductor laser and a detector for detecting the light beam reflected from the optical disk. Therefore the size of the optical head is reduced.
However, since the light emitted from the semiconductor laser and the reflected light from the optical disk interfere with each other on the surface of the detector A, a reproduced signal, a focussing error signal and a tracking error signal cannot be accurately obtained. Further, since reflected light from the objective lens or a member for supporting the objective lens interferes with light output from the semiconductor laser on the surface of the detector A, those signals cannot be accurately obtained.